wildfire:
my 2013 stralis doesn’t have a dog clip on my jost 5th wheel, doesn’t need one got drop down bar.
had many an argument with some vosa wheeltappers about that, my argument was you wouldnt use a lock too lock the lock on your house, never won though
mrginge:
bigtruck:
mrginge:
I don’t know if it was normal back in the old days (oldest truck I have driven is my current 2003 Scania tractor unit) but when using a 1988 Scania I didn’t realise till I wanted to drop the trailer you had to pull 2 levers.I think you’ll find the second lever is for sliding the plate forwards and backwards.
That’s what I originally thought but it wasn’t. I just assumed that must be how it used to be.
I can remember (vaguely) fifth wheels with 2 levers, then the York Big D came along with the single lever, I was only little then, and the Romans hadn’t invaded yet,
I bet Bewick & Harry Gill will know what I’m on about !!
check the handles out…ram the trailer,drop clutch a couple of times in a forward gear…if your still hooked up,happy days,wind the legs,do the rest and down the road… if your sitting at the docks and watch any driver hooking up,then that would appear to be the norm…not much more to it than that?..unless you want to take out your portable torque wrench and x ray machine to look for hairline cracks that might suddenly open up …( I bet they wish they had done that on the rivets on the titanic). 
if you can drop the dog clip in the
hole there’s a fair chance the jaws are locked
stevieboy308:
Bking:
Sorry gents but I have to say that if you believe a 50p [zb] dog clip means the difference between holding or not 30 tonnes or 240 000 newtons of load on the back of a tractor then what can you say!Even YOU cant believe this [zb] please?
30 tonnes or 240000 newtons…eh?
30 tonnes = mass 240000 newtons = force
30 tonnes static loading 240000 newtons force imposed on table bed on corners etc
1 newton = 1 kg at 1 G = 1 kg at 9.8 mtr per second squared
In other words the table will take 240 tonnes of side thrust before it breaks
Bking:
stevieboy308:
Bking:
Sorry gents but I have to say that if you believe a 50p [zb] dog clip means the difference between holding or not 30 tonnes or 240 000 newtons of load on the back of a tractor then what can you say!Even YOU cant believe this [zb] please?
30 tonnes or 240000 newtons…eh?
30 tonnes = mass 240000 newtons = force
30 tonnes static loading 240000 newtons force imposed on table bed on corners etc
1 newton = 1 kg at 1 G = 1 kg at 9.8 mtr per second squared
In other words the table will take 240 tonnes of side thrust before it breaks
eh…?
30 tonnes = 294199 newtons
force = mass x acceleration
1 newton = 0.102kg at 1g to 3 decimal places
1kg = 9.81 newtons at 1g
how much g do you think an artic can pull in the bends?
Bking:
stevieboy308:
Bking:
Sorry gents but I have to say that if you believe a 50p [zb] dog clip means the difference between holding or not 30 tonnes or 240 000 newtons of load on the back of a tractor then what can you say!Even YOU cant believe this [zb] please?
30 tonnes or 240000 newtons…eh?
30 tonnes = mass 240000 newtons = force
30 tonnes static loading 240000 newtons force imposed on table bed on corners etc
1 newton = 1 kg at 1 G = 1 kg at 9.8 mtr per second squared
In other words the table will take 240 tonnes of side thrust before it breaks
Weird how someone with supposedly 40 years of experience is spouting the sort of useless guff they pad out a City & guilds heavy vehicle technology textbook with of the sort an apprentice on a course would have - and not even spouting it correctly, what a surprise. 
30 tonnes of dead weight mass, under the influence of the earth’s gravity would be an equivalent force of 294,300 Newtons.
A rough approximation of the force exerted in the jaws of the fifth wheel could be derived from Newton’s second law but you would need figures for the acceleration or deceleration which in a lateral plane would not just be the acceleration of an object to earth due to gravity.
I find it amusing that the powers that be, EU,VOSA etc seem to be confused by the difference between mass and weight.
From Gov.UK :-
"Maximum authorised mass (MAM) means the weight of a vehicle or trailer including the maximum load that can be carried safely when it’s being used on the road.
This is also known as gross vehicle weight (GVW) or permissible maximum weight."
We used to have Max Gross Vehicle Weight, now we have Maximum Authorised Mass, they are not the same, in actual fact the gravitational force does vary over the earth’s surface.
Own Account Driver:
Bking:
stevieboy308:
Bking:
Sorry gents but I have to say that if you believe a 50p [zb] dog clip means the difference between holding or not 30 tonnes or 240 000 newtons of load on the back of a tractor then what can you say!Even YOU cant believe this [zb] please?
30 tonnes or 240000 newtons…eh?
30 tonnes = mass 240000 newtons = force
30 tonnes static loading 240000 newtons force imposed on table bed on corners etc
1 newton = 1 kg at 1 G = 1 kg at 9.8 mtr per second squared
In other words the table will take 240 tonnes of side thrust before it breaks
Weird how someone with supposedly 40 years of experience is spouting the sort of useless guff they pad out a City & guilds heavy vehicle technology textbook with of the sort an apprentice on a course would have - and not even spouting it correctly, what a surprise.
30 tonnes of dead weight mass, under the influence of the earth’s gravity would be an equivalent force of 294,300 Newtons.
A rough approximation of the force exerted in the jaws of the fifth wheel could be derived from Newton’s second law but you would need figures for the acceleration or deceleration which in a lateral plane would not just be the acceleration of an object to earth due to gravity.
No its called a vector.And this “useless guff” is clearly beyond you eh!
Any of you technically minded out there think it would be a good idea to make the fifth wheel wider now that trl chassis are wider,would it make tipping trailers more stable,and maybe help stop overturns on roundabouts and the like .
Bking:
Own Account Driver:
Bking:
stevieboy308:
Bking:
Sorry gents but I have to say that if you believe a 50p [zb] dog clip means the difference between holding or not 30 tonnes or 240 000 newtons of load on the back of a tractor then what can you say!Even YOU cant believe this [zb] please?
30 tonnes or 240000 newtons…eh?
30 tonnes = mass 240000 newtons = force
30 tonnes static loading 240000 newtons force imposed on table bed on corners etc
1 newton = 1 kg at 1 G = 1 kg at 9.8 mtr per second squared
In other words the table will take 240 tonnes of side thrust before it breaksWeird how someone with supposedly 40 years of experience is spouting the sort of useless guff they pad out a City & guilds heavy vehicle technology textbook with of the sort an apprentice on a course would have - and not even spouting it correctly, what a surprise.
30 tonnes of dead weight mass, under the influence of the earth’s gravity would be an equivalent force of 294,300 Newtons.
A rough approximation of the force exerted in the jaws of the fifth wheel could be derived from Newton’s second law but you would need figures for the acceleration or deceleration which in a lateral plane would not just be the acceleration of an object to earth due to gravity.
No its called a vector.And this “useless guff” is clearly beyond you eh!
Oh, oh, I see, it was some high falutin vector calculation that meant you arrived at a figure of 240,000 Newtons (despite you making no qualifying statement this was the case).
As it’s a vector force can you let me know what the vector coordinates, for the direction, are that makes the 240,000 Newton (now alleged) vector magnitude correct?
For simplicity, and to make it easy, we’ll assume standard Euclidean vectors operating a two-dimensional cartesian plane.
Any time you’re ready.
Trucknet just turned into truckmathsnet!
A fith wheel that supports a trailer mass on the pin of say, 20 odd tonnes can stand a sideways load of 200 odd tonnes? Blimey me,
Just curious how did you arrive at the lateral force it can take from the force supported vertically?
This thread is quality!
Freight Dog:
Trucknet just turned into truckmathsnet!A fith wheel that supports a trailer mass on the pin of say, 20 odd tonnes can stand a sideways load of 200 odd tonnes? Blimey me,
Just curious how did you arrive at the lateral force it can take from the force supported vertically?
I think his workings were,
30 tonnes = 240000 Newtons.
240000 Newtons = 240000 tonnes
Simples!
Just a little side note, the difference in what mine and own account driver’s figures for what 30 tonnes is equal to in newtons, was because I used a online converter which used all the decimal places and he used the standard accepted 9.81. Just on the off chance anyone was arsed!
My maths on this are slightly different.
30 ton plus a correctly locked fifth wheel, with a dog clip or spring clip, added to a 12 am delivery 200 miles away, at a starting time of 9am results in 10 cigarettes, 2 cans of redbull and my right foot pressed firmly down as if I’m trying to rest it on the headlight for 4 hours.
The result of all this is normally arriving late BUT bringing the original 30tons right along with me.
I can’t show my work for this maths however before anyone asks because I didn’t write it down.
kitbuilder123:
My maths on this are slightly different.
30 ton plus a correctly locked fifth wheel, with a dog clip or spring clip, added to a 12 am delivery 200 miles away, at a starting time of 9am results in 10 cigarettes, 2 cans of redbull and my right foot pressed firmly down as if I’m trying to rest it on the headlight for 4 hours.
The result of all this is normally arriving late BUT bringing the original 30tons right along with me.
I can’t show my work for this maths however before anyone asks because I didn’t write it down.
Yes but somebody has to work out the maths and we all take it for granted.
Maybe we should all show a bit more respect for the engineers who design and produce the “stuff” we all use and never give a second thought too.
Britain was once at the pinnacle of engineering excellence now (as Napolean said) we are a nation of bloody shopkeepers.
Bking:
Yes but somebody has to work out the maths and we all take it for granted.
Maybe we should all show a bit more respect for the engineers who design and produce the “stuff” we all use and never give a second thought too.
Spot on! But those engineers wouldn’t dream of claiming that the horizontal loading on a fifth wheel coupling gets anywhere near 240 tonnes. That kingpin would need to be made of some pretty exotic material to reliably withstand that. In fact they have a well understood standard equation for calculating it, and it is laid down in EU regs. The people such as SAF-Holland who make these things understand it pretty well, and the figure they quote as the maximum horizontal force for a standard 2" pin (EU regs require that the coupling, when tested, must be able to withstand this force without bending or cracking) is not 240 tonnes, not 200 tonnes, nor even 100 tonnes. 50 tonnes, maybe? Think a bit lower. 170kN - which works out to roughly 17.3 tonnes.
In order for cornering forces to approach 240 tonnes you’d have to be whipping the trailer round with the tyres off the ground (or at least, really well greased) like an olympic hammer thrower. At this point, fifth wheel failure would be rather low on your list of Things to Worry About!
Britain was once at the pinnacle of engineering excellence now (as Napolean said) we are a nation of bloody shopkeepers.
Maybe you need to go see your local shopkeeper and buy some new batteries for your calculator
Strange that .
A front king pin on a 44 tonne tractor withstands up to 4000 tonnes per cm of side thrust.
To put it “simply” for you the imposed load of a tractor will acording to Issac Newton try to “carry on in a straight line” Now if it amazes you that a 2 inch slug of high grade steel can withstand an imposed load of 4000 tonnes and you try to “lecture” the people on this forum about your “scientific” expertise do carry on.
Or do you have a deeper insight than Mr Newton
And yet a 5th wheel cannot support a load of 240 tonnes of side thrust.
You were the one doing the lecturing, my friend.
Anyway, 4000 tonnes per cm ? Now there’s a meaningless measurement - what is it supposed to be a measure of?
And while this 240 tonnes is pushing the thing sideways, what alchemy is at work keeping the tyres (more or less) gripping the road surface? The practical limit (without aerodynamic downforce - of which there is precious little with a metal box travelling at <56mph) on lateral acceleration is somewhat less than 1g without rails or some other system of physical restraint, yet apparently this limit doesn’t apply to lorries? Maybe it’s the deep ruts in the nearside lane? Do tell.